The generator matrix

 1  1
 0 a^6*X+1

generates a code of length 2 over F8[X]/(X^2) who´s minimum homogenous weight is 7.

Homogenous weight enumerator: w(x)=1x^0+112x^7+14x^8+3136x^14+784x^15+49x^16

The gray image is a linear code over GF(8) with n=16, k=4 and d=7.
This code was found by Heurico 1.16 in 3.1e-005 seconds.